# -*- coding: utf-8 -*-
# Copyright .
# Author:
#
# cython: language_level=3
#

import tensorflow as tf

def freeze_session(session, keep_var_names=None, output_names=None,
                   clear_devices=True):
  """
  Freezes the state of a session into a pruned computation graph.

  Creates a new computation graph where variable nodes are replaced by
  constants taking their current value in the session. The new graph will be
  pruned so subgraphs that are not necessary to compute the requested
  outputs are removed.
  @param session The TensorFlow session to be frozen.
  @param keep_var_names A list of variable names that should not be frozen,
                        or None to freeze all the variables in the graph.
  @param output_names Names of the relevant graph outputs.
  @param clear_devices Remove the device directives from the graph for better portability.
  @return The frozen graph definition.
  """
  graph = session.graph
  with graph.as_default():
    freeze_var_names = list(
      set(v.op.name for v in tf.global_variables()).difference(
        keep_var_names or []))
    output_names = output_names or []
    output_names += [v.op.name for v in tf.global_variables()]
    input_graph_def = graph.as_graph_def()
    if clear_devices:
      for node in input_graph_def.node:
        node.device = ""
    frozen_graph = tf.graph_util.convert_variables_to_constants(
      session, input_graph_def, output_names, freeze_var_names)
    return frozen_graph



def keras2pb(model):
  """
  将 keras 模型转 tf pb 模型
  Args:
    model:Keras model

  Returns:

  """
  from tensorflow.keras import backend as K
  import tensorflow as tf
  K.set_learning_phase(0)
  # input name, output name 在 Java 调用的时候需要.
  print(f"input: {[node.op.name for node in model.inputs]}")
  print(f"output: {[node.op.name for node in model.outputs]}")
  frozen_graph = freeze_session(K.get_session(),
                                output_names=[out.op.name for out in model.outputs])
  tf.train.write_graph(frozen_graph, "./model", "model.pb", as_text=False)
